None of us is neutral about insects. The strong emotional reactions they provoke have deep roots, says Jeffrey A. Lockwood in The Infested Mind

FEAR + Disgust = Horror. That was the feeling that overcame Jeffrey Lockwood as he was engulfed by a plague of grasshoppers. The rub is that this happened while he was working as an entomologist at the University of Wyoming. What should have been a routine check of his field experiment became a moment when insects wormed their way into his psyche. "The experience of being buried alive by life challenged... my mental health," he writes in his latest book, and it catalysed his move into the arts. He now teaches creative writing and philosophy.

In The Infested Mind, Lockwood takes us on a tour of our emotions surrounding insects and on to the wider world of mental health. These emotions aren't specific to zoological taxonomy, so spiders and other arthropods – animals with external skeletons, segmented bodies and jointed limbs – are all included.

No one is neutral about insects. Most of us are slightly wary of them, a few have a debilitating horror, and a very few have a love for them, one that rarely speaks its name: entomophilia.

It's perhaps because most of us aren't that keen on them that Lockwood's tour often struggles to engage the reader. The book does nicely clarify that where emotions are concerned, we are "culturally malleable creatures operating within evolutionary constraints". It points out that negative emotions towards insects are getting more common, at a time in our history when we are probably least exposed to them.

The surrealist painter Salvador Dalí had a terror of grasshoppers, brought on in his boyhood after other children tormented him with them. In his art, grasshoppers became symbols of waste and destruction. Dalí also found ants crawling over his dead pet bat – no wonder surrealism beckoned – and ants came to symbolise mortality and decay.

We know that our emotions are irrational, but this doesn't help where insects are concerned. Lockwood makes the point well; many people find it repulsive to eat arthropods such as grasshoppers, fed on fresh grass, but pay good money for other arthropods – lobsters – fed on sewage and decay. So why do insects get under our skin so much?

The evolutionary psychology answer is, to use Lockwood's phrase, "survival of the scaredest". In our history, those who quickly learned to be cautious about insects had greater evolutionary fitness and this, iterated over millennia, has got us to where we are now. This is why we are predisposed to be afraid of snakes. But none of these fears is very useful in our modern world. As Lockwood says – with a US perspective – it will be a while before we evolve the tendency to fear cars and guns in proportion to their likelihood of killing us.

Lockwood catalogues the central sources of our fears. What we really don't like about insects is that they can invade, bite and sting us, that they have quick, slithering movements and quickly growing populations, that their bodies seem weird and alien, and that they defy our will and control. Chillingly, he shows how people use their fear of insects to dehumanise enemies. The Nazi leader Heinrich Himmler thought anti-Semitism the same as delousing. During the Rwandan genocide, a Hutu-run radio station referred to ethnic Tutsi as cockroaches that needed to be exterminated. "Bugsplat" is the name some in the US government use for civilians killed by drones.

"Sleep tight, don't let the bedbugs bite" – remember that saying? You probably weren't bitten at all, but did begin to have bugs crawling into your mind. That's just part of being human.

This article appeared in print under the headline "Bugs on the brain"

Mark Viney is a biologist and studies parasitic worms at the University of Bristol, UK

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